Issue |
A&A
Volume 442, Number 1, October IV 2005
|
|
---|---|---|
Page(s) | 29 - 41 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20053232 | |
Published online | 30 September 2005 |
Internal dynamics of the z ~ 0.8 cluster RX J0152.7-1357
1
Dipartimento di Astronomia, Università degli Studi di Trieste, via Tiepolo 11, 34100 Trieste, Italy e-mail: girardi@ts.astro.it
2
ESO-European Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
3
Department of Physics & Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
Received:
12
April
2005
Accepted:
1
June
2005
We present the results from the dynamical analysis of the
cluster of galaxies RX J0152.7-1357, which shows a complex structure in its
X-ray emission, with two major clumps in the central region and a
third clump in the Eastern region. Our analysis is based on redshift
data for 187 galaxies. We find that RX J0152.7-1357 appears as a well
isolated peak in the redshift space at , which includes 95 galaxies recognized as cluster members. We compute the line-of-sight
velocity dispersion of galaxies,
km s-1, which is significantly larger than what is expected in the
case of a relaxed cluster with an observed X-ray temperature of 5-6
keV. We find evidence that this cluster is far from dynamical
equilibrium, as shown by the non Gaussianity of the velocity
distribution, the presence of a velocity gradient and a significant
substructure. Our analysis shows that the high value of
is due to the complex structure of RX J0152.7-1357, i.e. to the presence
of three galaxy clumps of different mean velocities. Using optical data
we detect a low-velocity clump (with
–500 km s-1)
in the central southwest region and a high-velocity clump (with
km s-1) in the Eastern region,
corresponding well to the South–West and East peaks detected in the X-ray
emission. The central North–East X-ray peak is associated to the
main galaxy structure with a velocity which is intermediate between
those of the other two clumps and
km s-1. The
mass of the whole system within 2 Mpc is estimated to lie in the range
, depending on the model adopted to
describe the cluster dynamics. Such values are comparable to those of
very massive clusters at lower redshifts. Analytic calculations based
on the two-body model indicate that the system is most likely bound
and currently undergoing merging. In particular, we suggest that the
southwestern clump is not a small group, but rather the dense
cluster-core of a massive cluster, most likely destined to survive tidal
disruption during the merger.
Key words: galaxies: clusters: general / galaxies: clusters: individual: RX J0152.7-1357 / galaxies: distances and redshifts / cosmology: observations
© ESO, 2005
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.